Exercise interventions that focus on muscle strength and quality of life after cancer treatment appeared most effective among patients with low baseline values.

However, when applied during treatment, the interventions appeared to benefit patients equally regardless of baseline values, according to results of a meta-analysis of data from the POLARIS study.

“This finding indicates that, when using exercise for rehabilitation after cancer treatments, it may be useful to target specific exercise interventions to patients with low muscle strength and poor quality of life,” Laurien M. Buffart, PhD, researcher in the department of epidemiology and biostatistics and medical oncology at Amsterdam University Medical Center, and colleagues wrote. “Likewise, when aiming to benefit fatigue and physical function during and [after] cancer treatment, exercise interventions should be targeted to patients with high levels of fatigue and low levels of physical function, because they show the most benefits on these outcomes.”

The POLARIS study evaluated the effects of exercise and/or psychosocial interventions on quality of life among adults with various cancer types.

In their meta-analysis, Buffart and colleagues pooled data on 4,519 patients from 34 randomized trials included in the POLARIS study. Researchers used linear mixed-effect models to assess whether moderator effects of baseline values on exercise intervention outcomes differed during or after treatment.

Investigators observed a statistically significant effect on physical function when baseline physical function was less than 1 standard deviation greater than the mean. Additionally, a statistically significant effect on fatigue was observed when baseline values were at least 1 standard deviation less than the mean.

The effects of intervention during treatment on aerobic fitness were greater among patients with better baseline aerobic fitness (P = .002), which researchers described as an unexpected and counterintuitive finding.

“This finding suggests that a minimum level of aerobic fitness may be needed to obtain an aerobic fitness response to an exercise intervention during cancer treatment,” researchers wrote. “Perhaps, despite often being tailored to a patient’s capacity, exercise interventions during intensive cancer treatment may be too difficult for patients with low aerobic fitness.”

Although exercise should be encouraged for most patients with cancer, targeting specific subgroups may be especially beneficial and cost-effective, researchers wrote.

“Our findings on moderator effects of baseline values should be confirmed in large single studies with homogeneous patient populations, uniform treatment protocols and validated outcome measures,” Buffart and colleagues wrote. – by Jennifer Southall

Disclosures: Buffart reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.